I do not have to provide anything, as I said I have them and use them for years is true (14) that copies (7), the difference is only in your head and probably in the fact that the Chinese copies you just purchased b-grade (which cost less) and not a-grade.
it is logical that the 7075 is more resistant to shocks of 6061 … but no one ever denigrated products CLYW, the General-YO, the 1Drop, etc. and they are committed with the same material of the Chinese copies of YYR … so where’s the problem? in prejudice of people who do not look past over to the name of a brand … and I repeat, no one ever take away from his head that even the original YYR were machined from the same industry in China who made copies … all in agreement with Kengo itself (clearly years later when that model has now made its history, clearly also creating utilities for YYR same … maybe lowering the production cost of the original ones, while people over another economic yoyo take what, we see that they are still a product of YYR and maybe with time takes his voglis buying one original, to see how much better … (little… imho)
P.S. the Sleipnir to 63 grams. has its perfect weight … only after having been able to enjoy it with the copy I understood why the few bought the Jealousy (Kazuma Ohno signature proto ever released permanently) so they spoke well of what yoyo! Substantially was a Sleipnir of 56 mm diameter, 42 mm in width and 62.7 gr. of weight.